Creativity cannot be taught. It can only be encouraged and developed. As long as the teacher (or instructor) is leading, there will be no creative thought. Ask questions, listen, listen, listen, and give students time to think. Sometimes a whole class period ( an arbitrary division of time that inhibits creativity) needs to be allowed to pass before an original thought will emerge. It has been my experience that the quiet student is probably the most creative one in the room. So, ask questions...and listen to the answers.
If, as the teacher, you are uncomfortable with creativity, don't try it. Just lecture on. If you have discovered something that has brought a new thought into your head, share the trill of creativity and allow the students to "catch fire".
There are many critics, but very little critical thinking. Critical thinking results when the other person is asked why.Critical thinking is destroyed by an authoritative analysis of the answer. The critic may be right, or maybe wrong, the point is to produce an analysis that satisfies the investigator.
These two points are best served by an honest answer as to the purpose of an education. Why are we in school?